Question

Решите плз:
5*9^х+9^х-2=406

Answer 1

$5*9^x+9^{x-2}=406\ \ 5*9^x+frac{9^x}{81} =406\ \ 5*81*9^x+9^x=406*81\ \ 405*9^x+9^x=406*81\ \ 406*9^x=406*81\ \ 9^x=81\ \ 9^x=9^2\ \ x=2$